As energy consumption rises, the control of voltage at generating plants remains a challenge to improved stability of such plants. To ensure uninterrupted generation and delivery of power, enhancement of grid reliability may be realized by taking a number of actions including, but not limited to: (i) resolving local and regional reliability problems; (ii) minimizing the potential for common mode failures associated with major disturbances and, or large-scale events such as weather-related phenomena; and (iii) sharing resources by interconnecting distant synchronous networks.
Technical limitations inherent to AC systems, however, have increasingly rendered such measures ineffective. For load zones, such conditions arise when the local network reaches a level of maturity (density) that prevents the addition of either generation or AC circuits without causing short-circuit capacity problems. For networks connecting generation clusters, the AC limitations may manifest themselves in overvoltage and N-1 and N-1-1 operational constraints. Moreover, AC interconnection of control areas can at times be counterproductive when it leads to exacerbating the common mode failure problem for the larger grid.
A need therefore exists to avoid AC limitations on enhancing grid reliability.